# Relic density and PAMELA events in a heavy wino dark matter model with Sommerfeld effect - High Energy Physics - Phenomenology

Abstract: In a wino LSP scenario the annihilation cross section of winosgravitationally bound in galaxies can be boosted by a Sommerfeld enhancementfactor which arises due to the ladder of exchanged W bosons between the initialstates. The boost factor obtained can be in the range S ~ 10^4 if the mass isclose to the resonance value of M ~ 4 TeV. In this paper we show that if onetakes into account the Sommerfeld enhancement in the relic abundancecalculation then the correct relic density is obtained for 4 TeV wino mass dueto the enhanced annihilation after their kinetic decoupling. At the same timethe Sommerfeld enhancement in the \chi \chi -> W^+ W^- annihilation channel issufficient to explain the positron flux seen in PAMELA data withoutsignificantly exceeding the observed antiproton signal. We also show that e^-+ e^+ and gamma ray signals are broadly compatible with the Fermi-LATobservations. In conclusion we show that a 4 TeV wino DM can explain thepositron and antiproton fluxes observed by PAMELA and at the same time give athermal relic abundance of CDM consistent with WMAP observations.

Author: Subhendra Mohanty, Soumya Rao, D.P.Roy

Source: https://arxiv.org/